Health and social care secretary Matt Hancock told MPs this week that the government was targeting a solution to the impact of pension taxes on the NHS workforce by the end of the current financial year.
But GPs and accountants have warned that failure to come up with a solution sooner risks leaving the NHS exposed this winter.
BMA GP committee chair Dr Richard Vautrey said: 'This is a problem that was of the government's own making - and the government can make changes as quickly as it wants. It will be a big problem for the NHS if there is no change before winter.
'Waits for GP appointments will get worse. Pressure on GP practices and on hospitals for appointments will get longer.'
Specialist medical accountant Andrew Pow, a partner at Mazars LLP and board member at the Association of Specialist Medical Accountants (Aisma) said many GPs who used to work eight sessions a week had dropped down to six.
Hospital consultants, meanwhile, were 'dropping like flies', he warned. 'There are three or four a week coming through our door who have never thought about this before and are now all considering dropping sessions. It is going to cause chaos in hospitals, and will have a knock-on effect on general practice.'
Other GPs took to social media to urge the government to act faster, with one warning: 'It is an emergency we are talking about here.'
Does it really take a whole department 9 months to do this? I should have thought that it was something that in principle could be decided over a weekend, with ten days to sort out the details. After all, it is an emergency that we are talking about here.— Dr John Lockley (@DrWJL) July 10, 2019
The warnings come after NHS Providers said this week that hospitals were being forced to delay surgery because of rota gaps. Chief executive Chris Hopson said: 'We have multiple trusts telling us they are expecting a significant increase in the number of surgery cases they will have to delay, leaving patients in pain and risking their problems getting much worse.
'Trusts are also worried that [pension tax] issues are one of the reasons for the current NHS performance problems in emergency care with April and May performance much worse than expected.'
BMA chair Dr Chaand Nagpaul warned earlier this year that doctors were being 'taxed out of the NHS', and GPonline reported in May that one in three GPs had been forced to reduce working hours or refuse extra shifts to avoid heavy taxes on pension contributions that can mean doctors effectively pay to take on extra work.
The 'massive loss of capacity' in the NHS predicted by BMA leaders as a direct result of the problem could leave the NHS in severe difficulties over winter.
Last year, despite relatively mild weather and a far more effective flu campaign than the previous year, average hospital bed occupancy rates hit 94% through the winter months.
NHS Providers has warned that over winter 2018/19 'the NHS saw its poorest ever performance against the cancer standards', while the elective care waiting list hit 'record levels'.
Mr Pow said that even if changes to the pension tax regime were not implemented until next year, concrete proposals could see doctors 'change their behaviour' - perhaps simply opting out of the NHS pension scheme in the short term rather than reducing hours or retiring.
However, the NHS looks set to be waiting some time for a solution. Mr Hancock said this week that a consultation on proposals to ease the problem - promised over a month ago - would be published 'as soon as possible'.
He was unable to say whether it would contain alternatives to the '50:50' scheme that would allow doctors to slow the growth of their pensions by halving contributions - a solution that the BMA has warned does not go far enough to stop doctors being forced out of work.
Accountants, the BMA and others have warned that the consultation must include alternatives to the 50:50 scheme. Mr Hopson warned this week: 'We can't wait for a long drawn-out consultation process on their initial proposal, which is the current plan.'
Mr Hancock told MPs this week that the impact of pension tax on the NHS workforce was 'very serious', and that he was 'absolutely determined to solve the problem'.